Wireless sensors are preferred for many applications because they can be deployed quickly and without wiring. The absence of wiring makes wireless sensors especially favored in applications where low weight is important, such as in aircraft applications. Wireless sensors typically contain an integral power supply, such as a battery and/or an energy-harvesting device, or other suitable power supply. Components related to signal transmission generally consume more power than other components in wireless sensor systems.
Some common wireless sensors include both a receiver and a transmitter. In these wireless sensors, the sensor's receiver is interrogated by another wireless device. The other wireless device requests that the sensor transmit data. The sensor's receiver receives the request to transmit data and the data is transmitted using the sensor's transmitter. While it is not necessary that the transmitter always be powered on, the receiver is typically powered on to receive requests because receivers are typically not aware of when a request will be received. Thus, the receiver is typically powered on, such that the sensor can receive the interrogation requests from the other device. In addition, the transmitter uses a relatively large amount of power when it transmits data from the sensor, relative to the total power usage of the sensor.